<template>
  <div>
    <div class="goods">
      <div class="menu-wrapper" ref="menuWrapper">
        <ul>
          <li class="menu-item" v-for="(good, index) in goods" :key="index" 
            :class="{current: index === currentIndex}"
            @click="clickMentItem(index)"
          >
            <span class="text bottom-border-1px">
              <img
                class="icon"
                :src="good.icon"
                v-if="good.icon"
              /> {{good.name}}
            </span>
          </li>
        </ul>
      </div>
      <div class="foods-wrapper" ref="foodsWrapper">
        <ul ref="foodsUl">
          <li class="food-list-hook" v-for="(good, index) in goods" :key="index">
            <h1 class="title">{{good.name}}</h1>
            <ul>
              <li class="food-item bottom-border-1px" 
                v-for="(food, index) in good.foods" 
                :key="index" @click="showFood(food)"
              >
                <div class="icon">
                  <img
                    width="57"
                    height="57"
                    :src="food.icon"
                  />
                </div>
                <div class="content">
                  <h2 class="name">{{food.name}}</h2>
                  <p class="desc">{{food.description}}</p>
                  <div class="extra">
                    <span class="count">月售 {{food.sellCount}} 份</span>
                    <span>好评率 {{food.rating}}%</span>
                  </div>
                  <div class="price">
                    <span class="now">￥{{food.price}}</span>
                    <span class="olg" v-if="food.oldPrice">￥{{food.oldPrice}}</span>
                  </div>
                  <div class="cartcontrol-wrapper">
                    <CartControl :food="food"/>
                  </div>
                </div>
              </li>
            </ul>
          </li>
        </ul>
      </div>
      <ShopCart />
    </div>
    <Food :food="food" ref="food"/>
  </div>
</template>

<script>
import BScroll from 'better-scroll'
import {mapState} from "vuex"
import CartControl from "../../../components/Cartcontrol/Cartcontrol"
import Food from "../../../components/Food/Food"
import ShopCart from "../../../components/ShopCart/ShopCart"

export default {
    data() {
        return {
            scrollY: 0,
            tops: [],
            food: {}, //需要显示的food
        }
    },
    components: {
      CartControl,
      Food,
      ShopCart
    },
    mounted() {
        this.$store.dispatch("getShopGoods", () => {
            //数据更新后执行
            this.$nextTick(() => { //列表数据更新显示后（其实不加这个也可以的）
                this._initScroll()
                this._initTops()
            })
        })
    },
    computed: {
        ...mapState(['goods']),
        // 计算得到当前分类的下标
        currentIndex() { // 初始和相关数据发生了变化
          // 得到条件数据  
          const {scrollY, tops} = this;
          //根据条件计算产生一个结果
          const index = tops.findIndex((top, index) => {
            //  scrollY >= 当前top && scrollY < 下一个top
            return scrollY >= top && scrollY < tops[index+1] 
          })
          //返回结果
          return index
        }
    },
    methods: {
        // 初始化滚动
        _initScroll() {
            //列表显示之后创建
            new BScroll(".menu-wrapper", {
                click: true
            })
            this.foodScroll = new BScroll(".foods-wrapper", {
                probeType: 2
            })
            /**
             * 这个和swiper一样，需要等到列表数据都有了之后再创建这个
             */
            //给右侧列表绑定scroll监听
            this.foodScroll.on("scroll", ({x, y}) => {
              this.scrollY = Math.abs(y);
            })
            //给右侧列表绑定结束监听
            this.foodScroll.on("scrollEnd", ({x, y}) => {
              this.scrollY = Math.abs(y);
            })
        },
        // 初始化tops
        _initTops() {
            //1. 初始化tops
            const tops = [];
            let top = 0
            tops.push(top)
            //2. 收集
            //找到所有分类的li
            const lis = this.$refs.foodsUl.getElementsByClassName("food-list-hook")
            Array.prototype.slice.call(lis).forEach(li => {
                top += li.clientHeight;
                tops.push(top)
            })
            //3. 更新数据
            this.tops = tops;
        },
        clickMentItem(index) {
          // 使右侧列表滑动到对应位置
          // 得到目标位置的scrollY
          const y = this.tops[index]
          // 立即更新scrollY（让点击的分类项成为当前分类）
          this.scrollY = y
          // 平滑滚动右侧列表
          this.foodScroll.scrollTo(0, -y, 500)
        },
        showFood(food) {
          // 设置food
          this.food = food;
          // 显示food组件(调用子组件对象方法)
          this.$refs.food.toggleShow()
        }
    }
};
</script>
<style lang="stylus" scoped>
  @import "../../../common/stylus/mixins.styl"
  .goods
    display: flex
    position: absolute
    top: 195px
    bottom: 46px
    width: 100%
    background: #fff;
    overflow: hidden
    .menu-wrapper
      flex: 0 0 80px
      width: 80px
      background: #f3f5f7
      .menu-item
        display: table
        height: 54px
        width: 56px
        padding: 0 12px
        line-height: 14px
        &.current
          position: relative
          z-index: 10
          margin-top: -1px
          background: #fff
          color: $green
          font-weight: 700
          .text
            border-none()
        .icon
          display: inline-block
          vertical-align: top
          width: 12px
          height: 12px
          margin-right: 2px
          background-size: 12px 12px
          background-repeat: no-repeat
        .text
          display: table-cell
          width: 56px
          vertical-align: middle
          bottom-border-1px(rgba(7, 17, 27, 0.1))
          font-size: 12px
    .foods-wrapper
      flex: 1
      .title
        padding-left: 14px
        height: 26px
        line-height: 26px
        border-left: 2px solid #d9dde1
        font-size: 12px
        color: rgb(147, 153, 159)
        background: #f3f5f7
      .food-item
        display: flex
        margin: 18px
        padding-bottom: 18px
        bottom-border-1px(rgba(7, 17, 27, 0.1))
        &:last-child
          border-none()
          margin-bottom: 0
        .icon
          flex: 0 0 57px
          margin-right: 10px
        .content
          flex: 1
          .name
            margin: 2px 0 8px 0
            height: 14px
            line-height: 14px
            font-size: 14px
            color: rgb(7, 17, 27)
          .desc, .extra
            line-height: 10px
            font-size: 10px
            color: rgb(147, 153, 159)
          .desc
            line-height: 12px
            margin-bottom: 8px
          .extra
            .count
              margin-right: 12px
          .price
            font-weight: 700
            line-height: 24px
            .now
              margin-right: 8px
              font-size: 14px
              color: rgb(240, 20, 20)
            .old
              text-decoration: line-through
              font-size: 10px
              color: rgb(147, 153, 159)
          .cartcontrol-wrapper
            position: absolute
            right: 0
            bottom: 12px
</style>